day 3

Author: sachuverma

Leetcode Daily Challenge/March-2021/03. Missing Number.cpp

@@ -0,0 +1,51 @@
+/*
+Missing Number
+==============
+
+Given an array nums containing n distinct numbers in the range [0, n], return the only number in the range that is missing from the array.
+
+Follow up: Could you implement a solution using only O(1) extra space complexity and O(n) runtime complexity?
+
+Example 1:
+Input: nums = [3,0,1]
+Output: 2
+Explanation: n = 3 since there are 3 numbers, so all numbers are in the range [0,3]. 2 is the missing number in the range since it does not appear in nums.
+
+Example 2:
+Input: nums = [0,1]
+Output: 2
+Explanation: n = 2 since there are 2 numbers, so all numbers are in the range [0,2]. 2 is the missing number in the range since it does not appear in nums.
+
+Example 3:
+Input: nums = [9,6,4,2,3,5,7,0,1]
+Output: 8
+Explanation: n = 9 since there are 9 numbers, so all numbers are in the range [0,9]. 8 is the missing number in the range since it does not appear in nums.
+
+Example 4:
+Input: nums = [0]
+Output: 1
+Explanation: n = 1 since there is 1 number, so all numbers are in the range [0,1]. 1 is the missing number in the range since it does not appear in nums.
+
+Constraints:
+n == nums.length
+1 <= n <= 104
+0 <= nums[i] <= n
+All the numbers of nums are unique.
+*/
+
+class Solution
+{
+public:
+  int missingNumber(vector<int> &nums)
+  {
+    unordered_map<int, int> m;
+    for (auto &i : nums)
+      m[i]++;
+    for (int i = 0; i <= nums.size(); ++i)
+    {
+      if (m[i] == 0)
+        return i;
+    }
+    return -1;
+  }
+};

Leetcode Daily Challenge/March-2021/README.md

@@ -4,3 +4,4 @@
 | :-: | :------------------------------------------------------------------------------------------------------------------------------------- | :-------------------------------------: |
 | 1.  | [Distribute Candies](https://leetcode.com/explore/challenge/card/march-leetcoding-challenge-2021/588/week-1-march-1st-march-7th/3657/) | [cpp](./01.%20Distribute%20Candies.cpp) |
 | 2.  | [Set Mismatch](https://leetcode.com/explore/challenge/card/march-leetcoding-challenge-2021/588/week-1-march-1st-march-7th/3658/)       |    [cpp](./02.%20Set%20Mismatch.cpp)    |
+| 3.  | [Missing Number](https://leetcode.com/explore/challenge/card/march-leetcoding-challenge-2021/588/week-1-march-1st-march-7th/3659/)       |    [cpp](./03.%20Missing%20Number.cpp)    |